N Is a Number: A Portrait of Paul Erdős is a 1993 documentary directed by George Paul Csicsery about the life of mathematician Paul Erdős. 　　Erdős himself appears in the film. As of 2007, using the official cast list in the credits, it gives Erdős a Bacon number (and thus Erdős-Bacon number) of 4. However, Sir Alec Guinness, identified by name by the narrator, appears in the film... (展开全部)